Potential Nutraceutical Properties of Vicia faba L: LC-ESI-HR-MS/MS-Based Profiling of Ancient Faba Bean Varieties and Their Biological Activity

<i>Vicia faba</i> L. is a widely cultivated legume known to contain numerous specialised metabolites. In this study, the seed coats and cotyledons of two ancient <i>V. faba</i> L. varieties, historically consumed in southern Italy and distinguished by black and purple seed coats, were extracted using 80% methanol and 80% ethanol. Extracts were analysed for total polyphenol, flavonoid and proanthocyanidin contents, and antioxidant activity using DPPH, ABTS, and FRAP assays. The purple seed coats exhibited the highest levels of phenolics and antioxidant capacity, exceeding those of black seed coats. Next, liquid chromatography coupled with high-resolution mass spectrometry (LC-ESI-HR-MS) was used to characterise the bioactive metabolites in both seed coats and cotyledons. The purple variety showed a higher phytochemical content, with a greater level of flavonoids and proanthocyanidins in methanolic extract. Furthermore, the purple seed coat exhibited in vitro anti-inflammatory activity by inhibiting soluble epoxide hydrolase (sEH), a key enzyme in the arachidonic acid cascade, with an IC₅₀ of 31.51 ± 1.16 µg/µL. Elemental analysis was performed for both varieties to assess their nutritional value. Specifically, the purple seed coats were found to represent a valuable source of bioactive compounds and micronutrients, highlighting their potential applications in nutraceutical, cosmetic, and food supplement sectors.